Ring expander



RING E XXXXX ma NNNNNN OR Patented Apr. 21, 1925.

GEORGE C. BECK, F SPOKANE, WASINGTO'.

RING EXPANDIR.

Application led Aug-ust 29, 1924. Serial No. 734,942.

a novel form of ring expander for expanding piston 'rings against the cylinder walls.

The prevailing expander now `iniuse consists of a crimped strip of clock spring steel, the crimped portions being uniform in size and the apices of the crimped portion being relatively sharply bent. This crimped strip is disposed in the piston groove between the base of the latter and the piston rin In use, the circular crimped strip is un er tension andthe alternately disposed and oppositely facing crimped portions, at their apices, engage the inner face of the ring and the periphery ofthe groove base and normally act to expand the ring against 'the cylinder walls.

As the average clearance between the ring and groove base is only twenty one thousandths of an inch, 4it has been the practice to use clock spring steel of an extremely thin gage. By 4reason of the sharply bent apices, engaging the ring and groove, thesev expanders quickly wore out, the main reason being that wear was intensively localized on the sharplybent apices of the necessarily thin steel.

It is the object of ploy a much greater `length of the spring strip for bearing engagement against the ring and groove base thereby greatly prolonging the life of the expander.

Another feature consists in utilizing the greater portion of the strip for bearing purposes, and a minor part for connecting the bearing or engaging portionsv with each other whereby the expander ciently force the ring against the cylinder walls.

A further crimping the strip in a en the resulting expander without employing a greater thickness of steel than is now in use. V

A further object is to insure abutting engagement of the curved surfaces of the ring ,and groove throughout the entire length of .the engaging portions of the strip.

My invention resides in the crimped strip,

feature consists in shaping or in the county of Spokane and State of my invention to emwill more eilimanner to strengthas an article of manufacture, and also in the combination of the strip expander with a piston and ring.

Other' features and objects of my invention will be more fully described in connection with the accompanying drawing and will be more particularly pointed out in and by the appended claims. In the drawings Fig. 1, is a vlew in side elevation of a completed strip shown'on a very large scalel Fig. 2, is an edge view of the same. Fig. 3, is an enlarged horizontal sectional view of a piston, taken' through a groove in position between ak ring and the base of the ring groove in the piston.k

Like characters of reference designate similar parts throughout the different figures of the'drawing.

lThe. device of my invention is designated as a whole at 1, and the saine is made up from a strip of clockspring steel, initially flat. Either before or after tempering,` I shape the strip 1 in a manner to carry out the features of my invention.

.In the most preferred form, the strip 1 is crimped or shaped tovprovide alternately disposed elongated engaging sections 2 and 3, the former, as shown, engaging. the inner face 4, of a piston ring 5, and the latter engaging the base 6 of a ring groove in a piston 7 One side wall of `the groove is indicated at 8. tions 2 and 3 are oppositely facing and preferably of equal length. The sections It will be noted that the sec.

' thereof, and showing my improved expander y 2 and 3 are united by relatively short con- 3. This, together with the relatively short length of thesections 9, with respect to the length of sections' 2 or 3, not only serves to" stifl'ensections 9, but also serves Vto stiifen the sections 2 and 3 along thenl endmost portions approximately as indicated by arrows 12 and 13. Consequentl the central portions 14 and 15 will be correspondingly weaker than the endmost portions ofsaid' sections 2 and 3.

In addition to the foregoing structure and advantages, it is a very great desideratum of my -invention to obtain such uniformity and continuity of engagement that the elongated engaging sections 2 and 3 will perform their otlice in the most efficient manner, thereby prolonging'the life of the expander.

In shaping the strip, I convexly arch the sections 2 and 3 on radii much shorter than the radii of the inner face 4. of the ring 5, and also shorter than the radii of base 6, of the piston groove. As will be clearly seen in Fig. 2, the sections 2 and 3 are arched to present convex faces toward the surfaces they are designed to engage. Now when these sections 2 and 3 are under load, as when the ring 5 is in place against a cylinder, these sections 2 and 3 flatten out and are under compression such as to not only make their engagement continuous with the length of their respective surfaces, but also, to make such engagement of substantially uniform pressure throughout the length of the sections 2 and 3thereby presenting large area and long wearing surfaces. By reference to Fig. 3, it will be clear that sections 2 and 3 are in continuous engagement throughout their length with their respective surfaces, namely 4 and 6. Thus, while the central portions 14 and 15 are initially or normally weaker than the endmo'st portions 12 and 13, before the expander is placed under load, this flattening 'of the arches to abutment against the surfaces of greater radii, serves to place the entire length of each elongated section 2 and 3, under tension. When the strip is bent to circular form and disposed in the groove, the radially outwardly facing sections 2, are thereby arched even more than is indicated in Fig. 2, before the strip 1 is bent, which is an advantage.

' It will be noted that the sections 9, are not disposed on radial lines with respect to the piston 7, but on the contrary, are in diverglng relation. Hence, it will be clear that on compression of the expander bythe ring 5, the entire expander can spread circumferentially in the groove, if necessary, to compensate for any probable contraction of the ring 5. As it is usual not to bring the ends of the expander in actual contact, such circumferential contraction ofthe expander would not result in interference of the ends.

It has been stated that sharp bends are objectionable but it will be clear that the relatively sharp bends 10 and 11 are so disposed with respect to the engaging sections that no locallzed Wear Can be CODCSIllTated thereon..

messed It is believed that the device of my invention will be fully understood from the foregoing description, and while I have shown and described one specific embodiment of .ring therein, comprising a spring metal strip shaped to form alternately disposed and oppositely facing elongated ring and groove engaging sections, said strip havingl relatively short supporting sections between the ring and groove sections.

3. A ring expander adapted to be disposed between the base of a piston groove and the ring therein, comprising a spring strip shaped to form alternately disposed and relatively weak elongated ring and groove engaging sections, and said strip having a relatively short and strong supporting section between the ring and groove engaging sections.

4. A ring expander adapted to be disposed between the base of a piston groove and the rin therein, comprising, a spring strip shape to form relatively weak ring and groove engaging sections and a relatively strong supporting section between the ring and groove engaging sections.

5'. A ring expander adapted to be dis posed between the base of a piston groove andthe ring therein, comprislng, a spring strip having convex groove and ring engagmg sections normally arched on shorter radii than the'radii of the groove and ring surfaces engaged thereby and adapted to Hatten under load to the radii of the surfaces engaged thereby.

ring expander adapted to disposed between the base of a piston groove and the ring held therein, comprising, a spring strip of uniform ycross `section bent to form relatively elongated oppositely facing and alternately disposed ring and groove engagingl sections, the connecting strip portions intermediate said sections being rela.- tively short and bent at relatively sharp angles at their junctures withi said. sections thereby4 rendering said connecting portions relatively stiff to form supporting sections for sai elongated sections and sti'en the latter near their endmost portions,l whereby the central `portions of said elongated Sections will the more readily fexif;

said elongated sections being normally arched on shorter radii than the radii of the groove and ring surfaces engaged therebyand adapted to flatten under load to the radii oi the surfaces engaged thereby, to insure a greater area Contact of saidelongated sections with their ring and groove faces.

7; A ring expander adapted to be disposed between the base of a piston groove and the ring therein, comprising, a strip shaped 1o lorin relatively elongated ring and groove engaging sections and relatively short connecting sections, whereby the major Aportion of the strip will be in engagement with the ring and groove surfaces.

8. In wml'iination, a piston having a groove and a ring therein, and a ring expander between the base of said groove and said ring and provided With a series of elongated bearing sections engaging said ring and a series of like elongated bearing sections the base of said groove, said bearing sections constituting a preponderence of the material of which said expander is formed.

9. A ring expander adapted to be disposed between the base of a piston groove and the ring' therein, comprising a striplike expander having elongated ring and groove engaging sections connected by relatively short supporting sections, said supporting sections being disposed on lines dlverging from the radii of the piston.

10. Aring expander adapted to be disposed between the base of a piston groove and the ring therein, comprising a resilient strip of uniform cross section having elongated ring and groove engaging sections stiiiened near their endmost portions and connected by supporting sections,.the saidv engaging sections being arched on lesser radii than the radii of the surfaces engaged thereby to flatten into continuous engagement with such surfaces under load. i

In testimony that I claim the foregoing as my own, I hereby ailix my signature.

GEORGE C. BECK. 

